You could manually "add a non-steam game" in the tools and point a shortcut at your renamed executable. Right click the shortcut after you add it and change the name to a personally pleasing title and you're good to go.

Note that it won't actually log your game access like it would have if it were launching the game directly from a Steam direct link, but the overlay will function exactly the same as if you were, so you get about 6/8ths functionality that way.

It's sloppy but it works. Don't think there's a way to manually change official Steam shortcuts, as Steam tends to update/overwrite anything it deems to be out of place anyways. I had a widescreen patch in KotOR that Steam kept blasting out of the water. I know this is apples and oranges, but I'm just saying. ;p